Various elements can be used to cool an electronic circuit board and its components. For example, it is possible to attach a heat sink to all or some of the electronic circuit board so as to carry away the heat produced by the board to the outside like the frame in which the electronic circuit board can be fitted.
Any electronic circuit board comprises spots that have a higher temperature than the rest of the board. These hot spots correspond to the places containing certain components, for example processors. In order to improve the dispersal of the heat from these hot spots, it is possible to use heat pipes. The latter are long metal cylinders (for example made of copper or aluminum) containing a fluid such as water.
This water is in equilibrium between its gaseous phase and its liquid phase, in the absence of any other gas. In the portion of the heat pipe situated close to the component to be cooled, the water heats up and vaporizes while absorbing energy originating from the heat emitted by this component.
This gas then rises up the heat pipe to arrive close to a cooling system where it will be cooled, until it condenses in order to become liquid again, and give up energy to the ambient air in the form of heat.
An example of a solution incorporating a heat pipe is described in document U.S. Pat. No. 6,839,235. It is shown as a heat pipe/heat sink assembly where each heat pipe is attached to one end of the heat sink with the aid of a tin weld or else a thermally conductive adhesive. This attachment between the heat pipes and the heat sink brings about a dependency between the two elements both from the thermal and the mechanical viewpoint.
The thermal dependence involves a poor clearance of the heat from the components of the electronic circuit board. Specifically, the calories carried away from the hot spots are added to the calories of the other components of the electronic circuit board, the latter being carried away via the heat sink. This thermal dependence greatly slows down the carrying away of the heat.
The mechanical dependence between the sink and the heat pipes makes mass fabrication of the cooling device difficult because of a necessary attachment between the heat pipes and the heat sink.